Alkenylation of aromatic compounds

A year later, Milstein and co-workers described a ruthenium-catalyzed oxidative coupling of arenes with olefins. The reaction in which O2 can be directly used as the oxidant required CO pressure (6.1 atm.) and proceeded with good activities (up to TON = 88). Both, electron-donating substituents on the arene, and electron-deficient alkenes methyl acrylate) appeared to be the most efficient coupling partners. Low activities were obtained for 

CDC Reactions with Molecular Oxygen as the Terminal Oxidant 

Ar-H = chlorobenzene, benzene, anisole, naphthalene p-xylene, p-dichlorobenzene 

Intramolecular annulation of heterocycles has been used as the key step in several total syntheses.Nevertheless, only rare examples refer to the use of 

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The palladium(II)-assisted alkenylation of aromatic compounds has also been applied to the synthesis of heterocycles. A novel synthesis of pyrido[3,4-d] pyrimidines, pyrido[2,3-d]pyrimidines and quinazolines was developed by Hirota et al. [18] employing the palladium(ll)-promoted oxidative coupling of uracil derivatives and alkenes. l,3-Dimethyluracil-6-carboxaldehyde dimethylhydrazone (22), 6-dimethylaminomethylenamino-l,3-dimethyluracil (24) and ( )-6-(2-dimethylaminovinyl) uracil (26) all reacted with methyl acrylate in the presence of stoichiometric Pd(OAc)2, producing pyrido[3,4-ii]pyrimidine 23, pyrido[2,3-if]pyrimidine 25 and quinazoline 27, each apparently arising from direct arylation, 6ti electrocycliza-tion, and elimination of dimethylamine, in 67%, 89% and 64% yields respectively (Scheme 9.3). 

Reoxidant in Palladium-Catalyzed Reactions. Cu(OAc)2 has been used as a reoxidant in the Wacker oxidation (CH2=CH2 + 02- CHsCHO) and in the Pd(OAc)2-catalyzed alkenylation of aromatic compounds with alkenes (eq 17). Pd(OAc)2 and Cu(OAc)2 are effective catalysts for the reactions... 

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